Conventionally, a silver paste has been mainly used for bonding a semiconductor element and a supporting member for mounting a semiconductor element. However, along with recent miniaturization/enhancement of the performance of semiconductor elements, miniaturization/densification has also been demanded for supporting members to be used. In spite of such a demand, it is difficult for the silver paste to deal with the demand due to the occurrence of defects in wire-bonding which are attributable to side drop thereof or an incline of a semiconductor element, the difficulty in control of a film thickness of an adhesive layer made from the silver paste, the occurrence of voids in an adhesive layer, and the like.
In view of this, in order to deal with the demand, a film-shaped adhesive has been used in recent years. This film-shaped adhesive is used in a singulated-piece attaching method or a wafer-back-surface attaching method. In the case of producing a semiconductor device by the singulated-piece attaching method with the use of a film-shaped adhesive, initially, one cuts a film-shaped adhesive wound up in a roll form (a reel form) into a given size by cutting or punching, so as to obtain a singulated piece of the film-shaped adhesive. A supporting member with a film-shaped adhesive is obtained by attaching this singulated piece to a supporting member for mounting a semiconductor element. After that, one produces a supporting member with a semiconductor element by bonding (die-bonding) a semiconductor element singulated by a dicing step to the supporting member with a film-shaped adhesive. Further, through a wire-bonding step, a sealing step, and the like as needed, one produces a semiconductor device.
However, when using a film-shaped adhesive in the singulated-piece attaching method, a special assembling apparatus for cutting and bonding the film-shaped adhesive to a supporting member is necessary, and thus a problem is that a production cost is higher than a method using a silver paste.
On the other hand, in the case of producing a semiconductor device by the wafer-back-surface attaching method using a film-shaped adhesive, initially, one attaches the film-shaped adhesive to a surface (a back surface) of a semiconductor wafer which surface is opposite to a circuit surface of the semiconductor wafer, and further, one attaches a dicing tape to a surface of the film-shaped adhesive which is opposite to a semiconductor-wafer side of the film-shaped adhesive. Then, a semiconductor element with a film-shaped adhesive is obtained by singulating the semiconductor wafer and the film-shaped adhesive into individual pieces by dicing. One picks up the obtained semiconductor element with a film-shaped adhesive, and bonds (die-bonds) to a supporting member for mounting a semiconductor element. After that, through steps of heating, hardening, wire-bonding, and the like, one produces a semiconductor device.
This wafer-back-surface attaching method using a film-shaped adhesive does not require any special apparatus for singulating film-shaped adhesives, since one bonds a semiconductor element with a film-shaped adhesive to a supporting member, and it is possible to use a conventional assembling apparatus for a silver paste without any modification or with partial modification of the apparatus such as adding a heating platen. In view of this, attention is attracted as a method that can restrain a production cost relatively low, among assembly methods of a semiconductor device using a film-shaped adhesive.
However, in the above wafer-back-surface attaching method using a film-shaped adhesive, before performing the dicing of a semiconductor wafer, two attachment steps are required, i.e., a step of attaching a film-shaped adhesive to a semiconductor wafer and a step of attaching a dicing tape to the film-shaped adhesive. In view of this, in order to simplify this process, an adhesive sheet (a die-bond dicing sheet) made by attaching a film-shaped adhesive to a dicing tape so as to have both functions thereof with one piece has been developed (for example, see Patent Literature 1). Such an adhesive sheet has, for example, a three-layer structure of a peeling base material, an adhesive layer, and a self-adhesive film.
Further, a method in which one processes such an adhesive sheet in advance into a shape of a wafer to constitute a semiconductor element (so-called pre-cut processing) has been known (for example, see Patent Literature 2). The pre-cut processing is a method in which: one punches an adhesive layer along a shape of a wafer to be used; one peels the adhesive layer except for a part for attaching the wafer; one attaches a dicing tape thereto; subsequently, one punches the dicing tape along a shape of a frame (a wafer ring) for use in wafer fixation in a dicing step; and one removes an unnecessary portion.
The adhesive sheet subjected to the pre-cut processing has a structure as shown in FIG. 1(a), for example. Further, FIG. 1(b) is an X-X end view of a sectioned part of a die-bond dicing sheet 200 of FIG. 1(a) in which an adhesive layer 2 is laminated on a peeling base material 1, and a self-adhesive film 3 is further laminated thereon so that a peeling base material 1 side is a surface having viscosity. Note that the self-adhesive film 3 is laminated so as to cover the adhesive layer 2 and to have contact with the peeling base material 1 around the adhesive layer 2, thereby making it possible to fix the adhesive sheet 200 by attaching the self-adhesive film 3 to a wafer ring of an outer periphery of a semiconductor wafer when performing the dicing of the semiconductor wafer.
In the case of performing such pre-cut processing, the adhesive sheet is generally produced by pre-cut processing an adhesive layer along a wafer shape in a film-shaped adhesive, attaching the film-shaped adhesive to a dicing tape, and subsequently performing the pre-cut processing of the dicing tape along a wafer-ring shape, or alternatively, by attaching a dicing tape which is pre-cut processed in advance into a wafer-ring shape to a film-shaped adhesive which is pre-cut processed in advance.